Fix typo in ReadTheDocs PR link automation

[mfisher87]

Woops! 🔔

The automation is adding the following to every PR:

📚 Documentation preview: https://jupytergis--285.org.readthedocs.build/en/285/
💡 JupyterLite preview: {docs-pre-index-url}/lite

But it should look like:

---

📚 Documentation preview: https://jupytergis--285.org.readthedocs.build/en/285/
💡 JupyterLite preview: https://jupytergis--285.org.readthedocs.build/en/285/lite

[github-actions]

👈 Launch a Binder on branch geojupyter/jupytergis/fix-rtd-pr-link-typo

[github-actions]

Integration tests report: appsharing.space

[brichet]

Thanks @mfisher87, LGTM

[mfisher87]

This did not resolve the issue. The action only supports one replacement because under the hood it's using JavaScript's String.replace method, which can only replace one occurrence. Modern versions of node support String.replaceAll.

readthedocs/actions#47

[brichet]

Good catch.
Maybe we should remove the jupyterlite preview for now (it is still available in the doc), and open a issue to track it.